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Vitamin E and homocysteine
IOWA CITY, IOWA. There is substantial evidence that homocysteine (a sulfur-containing amino acid)
promotes atherosclerosis and hypertension through increased oxidative stress and by causing a dysfunction
of the lining of the arteries (endothelial dysfunction) that results in reduced arterial blood flow. Earlier
research has shown that vitamin C can reverse endothelial dysfunction.
Researchers at the University of Iowa now report that vitamin E has a similar beneficial effect. Their
randomized, double-blind, placebo-controlled clinical trial involved 10 healthy volunteers who each went
through the four phases of the trial separated by at least a one-week washout period. The four experimental
protocols were:
- oral placebo at 7 a.m.
- L-methionine, 100 mg/kg bodyweight at 7 a.m.
- vitamin E, 1200 IU at midnight followed by placebo at 7 a.m.
- vitamin E, 1200 IU at midnight followed by methionine at 7 a.m.
L-methionine is known to sharply increase blood levels of homocysteine. Blood level of homocysteine and
blood flow through the forearm was measured six to eight hours after placebo or methionine administration.
The forearm blood flow was measured after an infusion of acetylcholine or bradykinin to simulate the body's
normal way of ensuring adequate blood flow. The researchers found that the high homocysteine levels
caused by the methionine administration very significantly lowered blood flow. The effect was completely
eliminated when vitamin E had been previously administered. They conclude that vitamin E, like vitamin C
effectively reverses the endothelial dysfunction caused by high homocysteine levels.
Raghuveer, Geetha, et al. Effect of vitamin E on resistance vessel endothelial dysfunction induced by
methionine. American Journal of Cardiology, Vol. 88, August 1, 2001, pp. 285-90
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